Evaluation of extent and amount of heterogeneous variance for milk yield in Uruguayan Holsteins

2001 ◽  
Vol 72 (2) ◽  
pp. 259-268 ◽  
Author(s):  
J. I. Urioste ◽  
D. Gianola ◽  
R. Rekaya ◽  
W. F. Fikse ◽  
K. A. Weigel
Keyword(s):  
Milk Yield ◽  
Phenotypic Variance ◽  
Simple Method ◽  
Factors Affecting ◽  
Lorenz Curves ◽  
Gini Coefficients ◽  
Adjustment Procedure ◽  
Contemporary Group ◽  
Lactation Length ◽  
Log Linear

AbstractThe extent and amount of heterogeneous phenotypic variance for milk yield in the Uruguayan Holstein population were evaluated and a simple method of accounting for heterogeneity was developed. Lactation records (159 169) collected between 1989 and 1998 by two recording schemes were used to form 8955 herd-year-season-parity-lactation length contemporary groups. A log-linear model was used to identify factors affecting heterogeneity of phenotypic variance. The model included effects of production level, contemporary group size, recording scheme, herd, season of calving, parity number, calving year period and length of lactation and accounted for 50% of the variation in log variances. Estimates from this model were used in a Bayesian manner, to obtain posterior mean estimates of within-contemporary-group variances, which were then used to standardize records to a baseline variance. Effects of the adjustment were assessed by comparing coefficients of variation before and after correction, by correlation and regression between mean and standard deviations, and by using Gini coefficients and Lorenz curves. The adjustment procedure reduced heteroscedasticity primarily by decreasing the frequency of low-variance contemporary groups. Lorenz curves and Gini coefficients indicated that the largest impact of the standardization procedure was related to the size of the contemporary group. Some differences in the effect of the correction were found between recording schemes. The method for adjusting records is simple and easy to adapt to current genetic evaluation procedures.

An analysis of the variation between dairy-sire progeny-groups for milk yield and fat content

1958 ◽  
Vol 1958 ◽  
pp. 19-29 ◽  
Author(s):  
Alan Robertson ◽  
S. S. Khishin
Keyword(s):  
Milk Yield ◽  
Comparison Method ◽  
Fat Content ◽  
Fat Percentage ◽  
Simple Method ◽  
Factors Affecting ◽  
Special Cases ◽  
The Mean ◽  
Milk Marketing ◽  
The Relationship

The past few years have seen the development in Great Britain of the ‘contemporary comparison’ method for evaluating progeny tests of dairy sires (Macarthur, 1954; Robertson, Stewart and Ashton 1956). The final overall figure attached to a sire is the mean difference between the yield of his daughters and that of other heifers milking in the same herd in the same year, with due regard for the numbers of animals in the two groups. Although it has some imperfections in special cases, this is probably the most informative simple method of evaluating a sire for yield and, fortunately, one which could be easily integrated with the existing recording system. The method has been turned into a simple routine in the Bureau of Records of the Milk Marketing Board and several thousand bulls have now been evaluated. In this paper, we shall be mostly concerned to use this material to investigate the heritabilities of milk yield and fat content and the relationship between the two in the different breeds. The information that we shall use consists, for each bull, of the mean contemporary comparison, with its effective ‘weight’, and the average fat percentage of the daughters. Before we deal with the observed results, we should go into rather more detail into the nature of these two figures and into the factors affecting them.

Partial milking of cattle in smallholder herds on the Accra Plains: some factors affecting daily partial milk yield and milk composition

1992 ◽  
Vol 54 (1) ◽  
pp. 15-21 ◽  
Author(s):  
S. A. Okantah
Keyword(s):  
Milk Yield ◽  
Milk Composition ◽  
Dry Season ◽  
Sub Saharan Africa ◽  
Factors Affecting ◽  
Stage Of Lactation ◽  
Lactation Length ◽  
Sub Saharan ◽  
Quadratic Effects ◽  
Accra Plains

AbstractDaily partial milk yield of Sanga cows in 13 smallholder agropastoralist herds at two locations on the Accra Plains was recorded through monthly sampling. Estimates of mean daily partial milk yield and milk composition were computed from 1266 observations. The unadjusted mean daily partial milk yield was 875 (s.e. 11) g. The composition of milk: total solids (TS), fat (F) and solid-not-fat (SNF) were 131 (s.e. 14), 41 (s.e. 11) and 90 (s.e. 7) g/kg respectively. Least squares estimate of mean daily partial milk yield were 808·2 and 462·4 g with average s.e. of 41·8 for wet and dry season respectively. The wet and dry season differences in daily partial milk yield, TS and F were highly significant (P < 0·01). Seasonal difference in SNF was not significant.Herd difference in partial milk yield, TS, F and SNF were highly significant (P < 0·02). There were no significant effects of location on daily partial milk yield and SNF, although location effects on F and TS were significant (P < 0·05). The highest milk yield was observed in cows in third lactation and the lowest in cows in seventh lactation (P < 0·01). Daily partial milk yield peaked in the 3rd month of lactation. On average, lactation length was 210 to 240 days. Both linear and quadratic effects of stage of lactation were highly significant (P < 0·01). Lactation curve parameters for partially milked cows were also estimated. The implications of the results for milk production in sub-Saharan Africa were discussed.

Use of ordered logit model with time series data for determining the factors affecting the milk yield of Holstein Friesians

2019 ◽  
Author(s):  
Özge Akkuş ◽  
Volkan Sevinç
Keyword(s):  
Time Series ◽  
Milk Yield ◽  
Logit Model ◽  
Time Series Data ◽  
Series Data ◽  
Ordered Logit ◽  
Factors Affecting ◽  
Ordered Logit Model ◽  
Lactation Length ◽  
Cattle Breeders

This article aims to introduce the use of ordered logit model with time series data in milk productivity studies and determine the important factor levels affecting the milk yield of Holstein Friesians. The data consists of 2002 records collected for the years 2009-2015 from the reports of the Cattle Breeders’ Association of Turkey (CBAT) in Muðla province in Turkey. The direct and marginal effects of the variables: parity, lactation length and year of calving on milk yield are investigated and the probabilities regarding the milk yield production for a given specific parity, lactation length and calving year are calculated. The results show that milk yield slightly increases on the 4th parity of cows. As far as the years concerned, although there had mostly been a steady amount of milk production between 2009 and 2015 years, there was a significant decrease in 2011 and increase in 2014.

scholarly journals Determining the Factors Affecting 305-Day Milk Yield of Dairy Cows with Regression Tree

2021 ◽  
Vol 9 (6) ◽  
pp. 1154-1158
Author(s):  
Serdar Genç ◽  
Mehmet Mendes
Keyword(s):  
Dairy Cows ◽  
Milk Yield ◽  
Regression Tree ◽  
Dry Period ◽  
Data Set ◽  
Tree Analysis ◽  
Factors Affecting ◽  
Lactation Length ◽  
Regression Tree Analysis ◽  
Service Period

The purpose of this study was to determine the factors affecting the 305-day milk yield of dairy cattle by using Regression Tree Analysis (RTA). The data set of this study consisted of 8 different cattle breeds grown in Turkey. Breed (B), Province (P), Lactation Length (LL), Service Period (SP), Dry Period (DP), Parity (PR), Calving Year (CY), Calving Age (CA) and Calving Month (CM) were used to predict the 305-day milk yield. Results of RTM showed that the usage of this method might be appropriate for determining the important factors that would be able to affect the 305-day milk yield (R2=71.3%). It was seen that the most important factors affecting the 305-day milk yield were the Breed, Lactation Length, Province, and Parity. Therefore, those selected factors were more efficient than the others in predicting the 305-day milk yield. RTA results also indicated that the lowest milk yield was estimated for Jersey, Jersey Crossbred, and Yerli Kara. Among the highest 305-day milk yield cows, the milk yield estimates of the cows in the second, third, fourth, fifth, and the sixth parities were found significantly higher than that of the cows in the first and seventh parities.

An analysis of the Entebbe herd of Nganda cattle in Uganda

1961 ◽  
Vol 3 (1) ◽  
pp. 29-39 ◽  
Author(s):  
P. Mahadevan ◽  
H. J. S. Marples
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Production Performance ◽  
Calving Interval ◽  
Indigenous Cattle ◽  
Factors Affecting ◽  
Lactation Length ◽  
The Government ◽  
To Come ◽  
Daily Milk Yield

In the herd of Nganda cattle at the Government Livestock Experiment Station, Entebbe, Uganda, it was found that of the known environmental factors affecting milk production, the more important ones were age (in lactations) and length of the calving interval preceding the second and third lactations. The correlations between performance in different lactations of the same animal were high for lactation milk yield (0·73) and average daily milk yield (0·62) and low for calving interval (0·21) and dry period (0·15). The repeatability of lactation length was intermediate (0·42). The heritability values were around 0·3 for the weight measurements, around 0·2 for yield characteristics and around 0·1 for length of lactation and age at first calving.The sires used in the breeding programme at Entebbe made little impact on production performance in the herd. The estimated genetic improvement in milk yield through selection of dams of cows was also low. It is argued from comparison with results from other parts of the tropics that superior genotypes for milk production are difficult to come by among indigenous cattle in these areas and that we should therefore look for other opportunities and methods to move ahead faster in the future.

Environmental and genetic factors affecting milk yield and quality in three Italian sheep breeds

2016 ◽  
Vol 84 (1) ◽  
pp. 27-31 ◽  
Author(s):  
Maria Selvaggi ◽  
Angela Gabriella D'Alessandro ◽  
Cataldo Dario
Keyword(s):  
Milk Yield ◽  
Genetic Factors ◽  
Quality Traits ◽  
Milk Traits ◽  
Factors Affecting ◽  
Sheep Breeds ◽  
Lactation Length ◽  
Yield And Quality ◽  
Lack Of Information ◽  
Heritability Estimates

The aims of the study described in the Research Communication were to determine the level of influence of some environmental factors on milk yield and quality traits, including lactose, and lactation length in ewes belonging to three different Italian breeds and to estimate the heritability for the same traits. A total of 2138 lactation records obtained from 535 ewes belonging to three different Italian breeds (Comisana, Leccese, and Sarda) were used. Breed significantly affected all of the considered traits. Moreover, year of lambing affected milk yield and lactation length without influence on milk quality traits. Parity affected significantly only the milk yield, whereas type of birth showed its effect on milk yield, fat, protein, and lactose yield. On the whole, the presently reported heritability estimates are within the range of those already obtained in other dairy breeds by other authors, with values for lactation length being very low in all the investigated populations. Considering the heritability estimates for lactose content and yield, to the best of our knowledge, there is a lack of information on these parameters in ovine species and this is the first report on heritability of lactose content and yield in dairy sheep breeds. Our results suggest that genetic variability for milk traits other than lactation length is adequate for selection indicating a good response to selection in these breeds.

scholarly journals Factors affecting lactation length and effect of current lactation length on the subsequent production and reproduction in Iranian Holsteins

2013 ◽  
Vol 56 (1) ◽  
pp. 873-881 ◽  
Author(s):  
N. G. Hossein-Zadeh
Keyword(s):  
Milk Yield ◽  
Reproductive Traits ◽  
Protein Yield ◽  
Fat Percentage ◽  
Factors Affecting ◽  
Protein Percentage ◽  
Lactation Length ◽  
Linear Relationships ◽  
Fat Yield ◽  
Increasing Trends

Abstract. Calving records of Holstein cows from January 1983 to December 2006 comprising 1,190 herds with 385,102 calving events were used to evaluate factors affecting the length of lactation and effect of current lactation length on the next productive and reproductive performances of Iranian Holsteins. Statistical analyses of productive and reproductive traits in this study were performed as linear mixed models. Lactation length (LL) of cows was grouped into 10 classes from <100 days through 500 days. Average LL was 314 days in Iranian Holsteins. Primiparous cows had the greatest LL and the mean of LL increased over the years from 1983 to 2006 and spring calvers had the longest LL (P<0.05). Cows within the LL class of 500 had the greatest unadjusted milk yield, adjusted milk yield, adjusted protein yield and adjusted fat yield and also had the longest calving intervals (P<0.05). Cows within the LL classes of 150–199 and 200–249 had the greatest values of adjusted protein percentage. Also, age at calving was the lowest for the LL class of 250–299 (P<0.05). There were linear and increasing trends for unadjusted milk yield, adjusted milk yield, adjusted protein yield and adjusted fat yield over the LL classes in this study, but a linear but decreasing trend was observed for adjusted protein percentage over LL classes. On the other hand, there were non-linear relationships between adjusted fat percentage, calving interval and age at calving with LL classes in the current study.

scholarly journals Factors Affecting Lactation Performance of Deoni Cattle

2020 ◽  
Vol 15 (04) ◽  
pp. 59-61
Author(s):  
Supriya G ◽  
Prashant Waghmare ◽  
Vivek Patil ◽  
Prakashkumar Rathod ◽  
Vidyasagar .
Keyword(s):  
Milk Yield ◽  
Genetic Factors ◽  
The Other ◽  
Age Group ◽  
Lactation Performance ◽  
Factors Affecting ◽  
Lactation Length ◽  
Performance Traits ◽  
Effect Of Age

The research was conducted on 78 lactation records of 78 Deoni cows over three years to analyze the effect of non-genetic factors on lactation performance traits. Data of lactation records were analyzed to determine the effect of age, parity, a period of calving and season of calving on lactation traits, viz., lactation milk yield (LMY), peak milk yield (PMY), lactation length (LL) and persistency of lactation. The findings revealed that age group and parity had a significant (p ≤0.05) effect on lactation milk yield, but not the period of calving and season of calving. Further, only the parity had a significant (P≤0.05) effect on peak milk yield of Deoni cattle but not the age group, period of calving, and season of calving. The other two traits, namely lactation length, and persistence was not influenced significantly by any the non-genetic factors evaluated in Deoni cattle.

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